books.google.fr - By the time of the Crusades, the Islamic world had developed its own sophisticated styles of fortification. Distinctive and highly effective, the region's unique military architecture continued to evolve in response to the Crusader and Mongol threats, and also drew upon the traditions of their foes and...https://books.google.fr/books/about/Saracen_Strongholds_1100_1500.html?hl=fr&id=XshAEMLqzmAC&utm_source=gb-gplus-shareSaracen Strongholds 1100-1500